Freezing studies Retrofitting the fezzes in Malargue Pablo Bauleo and David Warner Physics Department Colorado State University Fort Collins, CO 80523

A little bit of history Insulation Ice layer Ice formation around the dome and thaw-freezing cycles produces mechanical decoupling of RTV from dome Test performed on small tank in a walk-in freezer Thermal insulation around the fez and between fez and PMT prevents ice formation around the dome “Deep” freezing tests (up to 9 cm of ice) develops a thin ice layer of a few millimeters around the dome No mechanical decoupling of RTV with this configuration Freezing studies Colorado State P. Bauleo and D. Warner

Insulation used in Argentina Inner ring Outer ring Due to delay in IR production of about 280 tanks have been deployed without any thermal insulation Field mod calls for easy and fast retrofit Freezing studies Colorado State P. Bauleo and D. Warner

Retrofit kit “Tea cozy” design around the fez (replace the inner ring) Larger OD in outer ring to push the ice away Tests performed in small tank with walk-in freezer in Ft Collins Thick ice layer (7-8 cm) outside the insulated area  No ice around the dome Super thick ice layer (12-14 cm) outside the insulated area  1 cm of ice around the dome Freezing studies Colorado State P. Bauleo and D. Warner

Plans Finalize engineering details Get quote from vendor in Argentina Take a prototype to Malargue in November and make sure does not interfere with HV/base heat dissipation in summer Retrofit the tanks! As part of regular maintenance visits Retrofit campaign? Keep up the momentum and experience on freezing test for Auger North Freezing studies Colorado State P. Bauleo and D. Warner